1. numbers of BALF neutrophils and macro- study the expression of IL-la by fiber
2. phages at 3 days and 1 week after the challenge (TW > crocidolite > chrysotile >
3. exposure. Consistent with the acute inflam- RCF) may correlate with the reported
4. mation levels of TNF-a mRNA were pathologic potential of fibers (25 26).
5. greatest at 3 days after the exposure and Accordingly our approach may be useful